1. Field of the Invention
The present invention generally relates to a control apparatus for a vehicular automatic transmission equipped with an electronic throttle apparatus. More specifically, the present invention is directed to a technique capable of controlling an automatic transmission when an abnormal throttle operation occurs.
2. Description of the Related Art
A technique capable of controlling a synchronous mesh type automatic transmission is known from, for example, Japanese Patent Application Laid-Open No. sho 63-270252, which was laid open to the public in 1988. In this control technique, when a gear of an automatic transmission is changed, a throttle valve is controlled to be set to a valve closing side by actuating an electronic throttle apparatus, and engine power transmitted from an engine to the transmission is interrupted by energizing an electromagnetic clutch, and then, a gear-change stage (transmission gear stage) is changed by operating a transmission actuator.
In a vehicle equipped with the above-described electronic throttle apparatus, generally, a throttle control apparatus monitors a variety of sensors, actuators and microprocessors, and when the throttle control apparatus detects that such an abnormal condition happens to occur, it limits engine power. However, there is the case where a malfunction mode occurs which cannot be detected as an abnormal condition while the monitoring operation of the throttle control apparatus is performed. For this malfunction mode, for example, data of a target throttle opening degree saved in a RAM becomes error. In such a case, the throttle control apparatus can never limit the engine power although the abnormal throttle operation is carried out. As a result, this may cause a problem on safety drive.
The present invention is intended to obviate the above-explained problem encountered with the conventional control apparatus for the vehicular automatic transmission equipped with the electronic throttle apparatus, and accordingly, has an object to provide a control apparatus for a vehicular automatic transmission, which can firmly limit engine power when an abnormal throttle operation happens to occur, to thereby ensure a safety driving operation.
Another object of the present invention is to provide a control apparatus for a vehicular automatic transmission, by which an abnormal condition of a throttle actuator can be monitored based on the throttle opening control condition at a fully released position of an acceleration pedal so that when it is determined that an abnormal throttle opening degree takes place, the vehicle driving system is brought into a neutral condition, thereby avoiding the unintentional running of the vehicle.
To achieve the above-described objects of the present invention, according to one aspect of the present invention, there is provided a control apparatus for a vehicular automatic transmission comprising: a throttle actuator for opening/closing a throttle valve provided in an air intake pipe of an engine; a throttle opening sensor for sensing an opening degree of the throttle valve; a transmission having a shift lever and a plurality of gear-change stages for speed-changing a revolution force of the engine so as to transmit the speed-changed revolution force to a driven member, the plurality of gear-change stages being selectively switched over by the shift lever; a shift lever position detector for detecting a gear-change position of the shift lever; an accelerator sensor for sensing an operation amount of an accelerator pedal; a power transmitting clutch for establishing/interrupting power transmitted from the engine to the transmission; and a control unit for determining an abnormal throttle opening condition when the opening degree of the throttle valve sensed by the throttle opening sensor is not less than a predetermined value under the condition that the shift lever position is in a drive range and that the accelerator sensor senses a fully-released position of the accelerator pedal, the control unit being operable to control, upon determination of the abnormal throttle opening condition, the power transmitting clutch in such a manner as to place it into a power interrupting state.
According to another aspect of the present invention, there is provided a control apparatus for an automatic transmission comprising: a throttle actuator for opening/closing a throttle valve provided in an air intake pipe of an engine; a throttle opening sensor for sensing an opening degree of the throttle valve; a transmission for speed-changing a revolution force of the engine so as to transmit the speed-changed revolution force to a driven member; an accelerator sensor for sensing an operation amount of an accelerator pedal; a gear-change actuator unit for controlling the transmission to a desired gear-change ratio; and a control unit for determining an abnormal throttle opening condition when the opening degree of the throttle valve sensed by the throttle opening sensor is not less than a predetermined value under the condition that the accelerator sensor senses a fully-released position of the accelerator pedal, the control unit being operable to control, upon determination of the abnormal throttle opening condition, the transmission in such a manner as to place it into a neutral state.
In one preferred form of the invention, the control unit limits the power of the engine when it determines that the throttle opening condition is abnormal.
In another referred form of the invention, the control unit generates a warning when it determines that the throttle opening condition is abnormal.
In a further preferred form of the invention, when it is determined that the throttle opening condition is abnormal, the control unit limits, upon the accelerator pedal being stepped on, the power of the engine in accordance with an operation amount of the accelerator pedal, generates a warning and connects the power transmitting clutch.
In a still further preferred form of the invention, when it is determined that the throttle opening condition is abnormal, the control unit limits, upon the accelerator pedal being stepped on, the power of the engine in accordance with an operation amount of the accelerator pedal, generates a warning and controls the gear-change actuator unit so as to change the gear-change ratio of the transmission to a desired gear-change ratio.